What the Bible says about Salt as a Symbol of an Everlasting Covenant
(From Forerunner Commentary)
It has been common throughout history for people to confirm their agreements with each other by eating and drinking together, at which times salt is used. As salt was added to foods, not only for spice but also to preserve them from decay, it became a symbol of incorruptibility and permanence. A "covenant of salt" signified an everlasting covenant. In the Bible, salt also came to symbolize purity, perfection, wisdom, hospitality, durability, and fidelity.
Mike Ford
Salt